Developing a durable, memory-driven, CspZ-targeting Lyme disease vaccine by rational adjuvant selection

Rational adjuvant selection is a systematic approach based on adjuvant-mediated immunomodulation to identify safe vaccine regimens that enhance protective immunity. Transmitted through ticks and caused by the bacterium Borrelia burgdorferi (Bb), Lyme disease (LD) is the most common vector-borne disease in the Northern hemisphere. There are no approved human vaccines, making it suitable for testing the concept of rational adjuvant selection. Here, we formulated our previously developed and effective LD vaccine antigen, CspZ-YA_C187S, with different adjuvants suitable for human use; we analyzed the immune response by transcriptomics and tested the vaccine efficacy after Bb infection. We identified Alum-CpG and Alum-αGal to elicit the highest titers of CspZ-YA_C187S-dependent protective antibodies and robust levels of protection, but through distinct mechanisms of immunomodulation. We demonstrated that immunization with Alum-CpG formulated CspZ-YA_C187S provided up to nine months of protective bactericidal antibody titers, as well as recall-memory response to prevent LD after natural infection. Immunity was linked to elevated levels of IgG1 memory cells in the vaccine-triggered immune responses. This work thus identified a durable, memory immunity-driven LD vaccine, ultimately paving the road to understand the mechanisms of rationale adjuvant selection for vaccine development.